The reality is that DRM is a flawed model. In the end people just remove the DRM to get around such silliness.
In my Family since as long as I can remember one member would purchase a book. Then we would trade them and pass them along. Since reading a book is generally a one time thing and the cost is quite high for a new hard cover this has been a way to enjoy reading for all of us.
If publishers were smart they would allow a form of limited lending with standard drm intact. So that for instance in the case of my family only one member would be able to read a particular purchased book at a time. Allowing us to carry on the tradition electronically. Instead they make DRM restrictions so silly that you end up having to work around them.
I think long term this will become more of an issue. For instance the question can be asked what happens to your electronic purchases when the original license holder passes away? In the case of music files it has already been discovered by some families that extensive electronic collections purchased legally by an individual are not transferable later to family members. Imagine a parent or spouse dying and potentially leaving the family without access to any of the previously enjoyed music, books and movies because they were all under "Dad's account".
If the music and movie industries have any lessons to teach the publishing industry it's that if you charge too much or place too many restrictions on users they will simply find a way around the problem.